Your Heart Rate Is The Key To Smarter Sleep Stages Heres Why
If youve been using a Fitbit tracker to monitor your sleep, then you know how important movement is to signaling when you fall asleep, wake up, or stir. But in order to determine your sleep stageshow long you spend in light, deep, and Rapid Eye Movement sleepmovement alone is not enough.
During sleep studies, most sleep stages are scored based on brain waves, says Michael Grandner, MD, director of the Sleep and Health Research Program at the University of Arizona in Tucson and a Fitbit sleep consultant. Except during REM sleep when doctors are also looking for eye movements and a lack of muscle activity.
In other words, you cant determine light or deep sleep based on movement alone. You need another signal, says Grandner. You need something else that is going on in the body that differentiates REM from other stages of sleep.
So whats that second signal? Heres a hint: Its something many Fitbit trackers can already trackheart rate!
Galvanic Skin Response Sensor
Galvanic skin response sensor is one of those sensors that you dont hear much about. We suspect it has got something to do with its name. We could be wrong, of course. It measures the electrical conductivity of our skin.
The sensor analyzes our sweating patterns whether from exercising or something else. When this sensor is combined with the accelerometer, it can generate data that can use to understand how our body is responding to different exercises and help us do more of what works.
Fitbit May Track Sleep Time Accurately But Overestimate Problems
Your Fitbit might be doing a relatively good job of tracking your hours of sleep, but researchers warn its shortcomings can create more anxiety for those who struggle to rest.
Two small studies conducted by Monash University, published in the Journal of Sleep Research this week, found a Fitbit is comparable at measuring sleep time to clinical devices. However, when measuring the quality of a person’s sleep, wearable devices recorded the person as having a more shallow sleep than they actually obtained.
The Sleep Health Foundation estimates 1.5 million Australians suffer from sleep disorders. Credit:Shuttershock
In one study, researchers collected sleep data from 25 people with insomnia using both the Fitbit Alta HR and a research-grade actigraph over two weeks.
The second study, conducted on one night, saw 42 individuals with insomnia have their sleep measured by the wearable devices as well as polysomnography, a lab study involving a number of sleep indicators including brain activity, eye movement, muscle activity and heart rhythm.
Researchers concluded the Fitbit was equivalent to the actigraph in almost every way. Yet, when compared with polysomnography, the Fitbit was largely underestimating deep and REM sleep, missing roughly half of the former and a third of the latter. It also overestimated light sleep.
The Fitbit recorded an average of 50 minutes more total sleep than polysomnography, a figure in line with previous studies.
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What Happens If I Dont See Any Sleep Stages
There are some reasons why you might not see the report of your sleep stages and they are:
- The position you slept in prevented your Fitbit from getting a consistent measure of your heart rate or you ended up wearing it too loosely. To improve the results, wear your device higher on your wrist when possible and it should feel secure but not too tight.
- If you have used the Begin Sleep Now option on the app instead of simply wearing your device when going to bed, it may show some inaccurate details.
- If you have slept less than three hours of if your devices battery is critically low, the data may not be reflected.
For additional information on your recorded sleep pattern, you can tap on the sleep record that appears on the sleep pattern.
Estimated Oxygen Variation Graph Explained
Unlike some devices that will give you a number for your blood oxygen level. However, a Fitbit spokesperson told us that the graph provided by Fitbit is an “estimation of the variability of oxygen levels in the bloodstream”.
It’s not a graph of the actual Sp02 estimate.
The example screenshot above shows what the graph will look like and from what we can see, blood oxygen is monitored by the sensor during sleep and variations which could show a sleep apnea issue are highlighted on the graph.
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“We’re showing a metric which correlates with the average variability of your blood oxygen level,” said Dr. Conor Heneghan.
“Lets say Person A has oxygen level of 96% +/-1% and Person B has oxygen level of 95% +/- 4% throughout the night, then Person B will see a higher estimated oxygen variation throughout the night. We calculate this every minute.”
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What Kind Of Sleep Tracking Does It Do
Sleep tracking is one step towards a better nights sleep. By seeing how much youre actually sleeping, you can work towards better sleep goals. Not only does the Fitbit Inspire track sleep, it also allows you to set silent vibration alarms and bedtime reminders. Going to sleep and waking up at roughly the same time each day is another step towards better sleep habits.
Because the Fitbit Inspire doesnt track heart rate, it cant determine if youre in light, deep, or REM sleep.
Because the Fitbit Inspire doesnt track heart rate, it cant determine if youre in light, deep, or REM sleep. Rather, it can only see your total time asleep based on your nighttime movement. If you dont move at all, the Fitbit Inspire will automatically log that as sleep time. If you toss and turn and change positions in bed, the Inspire will register that as a restless state. If you move so much that it would be impossible to be asleep, such as getting up and walking to the bathroom, then the Inspire will register that as awake time.
The app will calculate your total sleep time per night by subtracting your restless and awake time from the total time tracked. For example, if you slept for eight hours, but you were restless for half an hour and awake for half an hour, the time asleep will show seven hours.
Fitbit Estimated Oxygen Variation: We Explain Spo2 Sleep Apnea And Blood Oxygen
In January 2020 Fitbit turned on its long awaited blood oxygen detection feature. Since 2017 its been packing an SpO2 sensor into its leading devices, but hasnt used the data. Until now.
Blood oxygen can be used to detect sleep conditions such as sleep apnea, and offer a better analysis of whats going on with our bodies in those lost hours.
But Fitbits Estimated Oxygen Variation data needs a little explanation. We spoke to Dr. Conor Heneghan, Fitbits Lead Sleep Research Scientist for everything you need to know.
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Fitbit Flex 2 Review: Accessories
The Flex 2 wristband is available in Black, Lavender, Magenta and Navy. You get both a Small and a Large wristband when you buy the Flex 2.
The Fitbit Flex was one of Fitbits longest-surviving trackers in its range, and for good reason it was slim, and so lightweight you forgot you were wearing it. Its update, the Flex 2, is even slimmer and comes with a range of accessories that suggest Fitbit is aiming this tracker at women or very confidently fashionable men
You can wear the Fitbit Flex 2 on your wrist in the slim band, in a bangle, or hung from a pendant. This is possible because the actual pebble-like tracker is removable, and be fitted into the three types of holder. Youll need it in the wristband to track your swimming. It can be in the Bangle, Pendant or Wristband for the other dry-land activity tracking as you prefer.
The hand-polished Bangle can be bought in Silver, Gold and Rose Gold colours. The Silver version is £10/$10/10 cheaper than the Gold versions.
The Pendant is available in either Silver or Gold, on a 17-inch chain. The Silver version is £10/$10/10 cheaper than the Gold version. Theres no Rose Gold version of the Pendant available yet.
Flex 2 owners can also buy two three-packs of wristbands. The Sport pack has bands in Grey, Yellow and Navy. The Pink pack in Magenta, Lavender and Blush Pink.
Theres just One Size but Fitbit includes both a Small and a Large wristband in the box.
Fitbit Charge 5 Review: The Verdict
The Fitbit Charge 5 is a good fitness tracker. It has features that most other trackers dont have, such as an EDA scanner. It has features reserved strictly for premium trackers, such as NFC payments support. It also features a bright, full-color OLED display, which immediately makes it aesthetically and functionally better than its predecessor.
However, its $30 price hike over the Charge 4s MSRP doesnt give you a better overall fitness tracker. Yes, the color display is objectively better than the monochrome one, but you need to sacrifice battery life and an altimeter for it. The EDA scanner is a cool touch, but how much will this metric matter to the average person?
The Fitbit Charge 5 is an OK fitness tracker. But why would you spend $180 on an OK fitness tracker?
For $180, the Fitbit Charge 5 should be the best fitness tracker ever. It should have all the fitness-focused features one would need to track all manners of workouts. It should have an altimeter, be able to track laps, and be able to have all 20 available workouts on the device at all times. Its battery life and effectiveness at health tracking should be unrivaled and all the promoted features should be available at launch. Yet the Charge 5 falls short of supplying every single one of those elements.
How Does Fitbit Track Sleep Duration
Fitbit uses this simple formula to determine our Sleep Duration.
Total time spent being awake or restless Total tracked time = Duration of your sleep.
This means if you have tracked 7 hours of sleep and spent 30 minutes being awake or tossing around in your bed, your Time Asleep will be 6 hours and 30 minutes.
Different Types Of Sleep
For tracking, Fitbit worked with sleep researchers and the National Sleep Foundation to highlight four specific types of sleep, which you see in a readout in the morning when you wake up.
Heres a breakdown, along with Fitbits explanation, of what each stage means:
Awake: When it comes to being awake during the night, many of us think that waking up at all is bad news. Turns out, waking up during the night is a normal part of sleep. In fact, waking up anywhere in the ballpark of 10-30 times in a single evening is normal.
So, if youre one of those people who roll over a few times during the night or get up to pee once or twice, youre just like everyone else. Theres nothing to be super worried about.
Light Sleep: Light sleep occurs when your body starts to slow down at night, its that moment when you start to fall asleep, but you could be easily woken. The best example is probably those moments when youre commuting and fall asleep on the train or in the passenger seat of your co-worker’s car. When youre in light sleep, you may be aware of what is going on around you, and someone can wake you up easily but youre still asleep.
During this sleep stage, your heart rate decreases slightly from what it is when youre awake. Just because you can be woken easily doesnt mean this isnt a useful stage light sleep helps a ton with mental and physical recovery, so you can feel better after an hour of light sleep than you did before you started to snooze.
Fitbit Flex 2 Review: The First Waterproof Fitbit
It is, however, only one of two Fitbit trackers that are fully waterproof and boast the ability to track swimming as an exercise.You have to enter the length of your pool in order to accurately count laps, and this is done via the Fitbit app. Were told that it works with front crawl , backstroke, breaststroke and butterfly. The other waterproof Fitbit is the high-end smartwatch read our Fitbit Ionic review.
You can wear it in the shower or bath, unlike the other only water-resistant trackers from Fitbit. Also, see our round-up of the best waterproof swim trackers. We think that the Flex 2 might even be used by some Fitbit enthusiasts as a second tracker specifically for the pool.
The Flex 2 is Fitbits first properly waterproof fitness tracker, and can track your swimming as an exercise activity. We havent fully tested the Flex 2 on a rigorous swim, but will update this review when we have. The Flex 2 measures your Swim Duration, and calculates calorie burn during your time in the pool.
Fitbit doesnt recommend extended exposure to water, so dont leave it in a bucket of water overnight. Like you would!
Yahoo tech columnist David Pogue spoke to a Fitbit product manager who admitted that even the Fitbit Charge 2 could be worn in the shower without damage, as long as the shower isnt super-powered. Pogue tried this out and had no problems with his Charge 2. But only the Flex 2 is guaranteed waterproof by Fitbit, and is the only Fitbit to actively track swimming.
Want More Information About Your Sleep Quality
Fitbit offers you additional insights into your sleep data, including analyzing your sleeping heart rate for Fitbit Premium subscription members.
The plan currently costs about USD 10 per month or USD 80 per year.
For sleep analysis, you also get a thorough breakdown of your sleep score along with personalized recommendations.
Plus, premium members get data on how restorative their sleep is via a Restoration score.
And Fitbit premium also offers guided programs that you use with your Fitbit device to get better sleep each night.
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Fitbit Vs Iphone Accuracy
Of course, phones have been counting steps for years before fitness trackers became popular. So how does the iPhones fitness tracking features compare to the Fitbit?
Eddie Smith, an actuary from Greenville, North Carolina, tested the two step counters against each other for several months. From December 23, 2014, to March 23, 2015, Smith discovered that the Fitbit logged 509,482 steps and 1,009 floors, while the iPhone logged 506,909 steps and 735 floors. The steps matched closely, but the Fitbit had counted significantly more floors.
After further testing, Smith concluded that this difference was probably due to how the two devices deal with steep terrain. The Fitbit uses its barometer to detect elevation changes, so it counts walking up steep terrain as floors. On the other hand, the iPhone measures floors when you literally walk up steps.
Get Tested For Sleep Apnea With Apneamed
If your Fitbit indicates that youre experiencing breathing disruptions throughout the night, it is beneficial to have a sleep study done to rule out conditions such as sleep apnea. Getting treatment, such as continuous positive airway pressure therapy, makes it possible for you to breathe easier, limiting the breathing disruptions that your Fitbit detected.
ApneaMed makes getting tested for obstructive sleep apnea more accessible than ever by providing individuals with an at-home sleep study that is delivered directly to your front door.
This self-administered sleep study is performed by you, allowing you to do it in the comfort of your own home. During the night, youll wear the monitoring device to record your blood oxygen levels, blood oxygen saturation, breathing, and heart rates, which will be analyzed by one of ApneaMeds board-certified sleep physicians. From there, ApneaMed will create a recommended treatment plan to ensure youre receiving a good nights sleep.
ApneaMed offers various home sleep tests and in-home breathing equipment to help treat obstructive sleep apnea. Contact our team to learn more.
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What Is Estimated Oxygen Variation
A reading of the oxygen levels in your blood, it uses a red LED in the optical heart rate monitor.
Fitbit’s detection is a little different. Rather than spitting out a single percentage score it examines the difference in the highs and lows of your blood oxygen, and looks to highlight potential underlying conditions.
However, that would require you checking and understanding the data.
Users of Inspire or Alta trackers don’t have the hardware inside, so won’t get the update.
The new feature has been rolling out pretty fast, starting in the US and we’ve already had our devices updated.
Sync Your Fitbit With The App
Its important to sync your Fitbit after waking up to see your sleep statistics in the Fitbit app.
So if youre missing your previous nights sleep information , make sure you sync before thinking something is wrong. It may not be!
You can manually sync your Fitbit by tapping the Sync Now button in the Fitbit apps device menu.
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What Is Fitbit Sleep Tracker
Fitbit sleep tracker is a feature is designed to give a detailed look into your sleeping patterns and help you adopt healthier habits. For this feature to work, you have to wear your Fitbit tracker to sleep. Once you wake up, youll find your sleep duration, awake time, and the time you spent on each sleep stage: light, REM, and deep.